Apparatus for metering liquid flow discharge

ABSTRACT

Apparatus for repetitively dispensing predetermined equal amounts of liquid metal from a container under uniform pressure in which the time of actual discharge from the container is maintained constant by detecting the initiation of discharge and terminating pressure application at a fixed time interval after initiation of discharge.

Lesher I [54] APPARATUS FOR METERING LIQUID FLOW DISCHARGE [75]lnventorz Elroy W. Lesher, Reading, Pa.

a 19605 [73] Assignee: Albany International Corp., Albany,

221 Filed z "Nov. 20,1956 M W '21 Appl. No.: 91,480

[52] US. Cl. ..222/70, 164/309, 222/394 [51] Int. Cl. ..B22d 37/00 [58]Field of Search ..222/D1G. 12, D16. 15, 394, 222/70; 164/136, 309

[56] References Cited UNITED STATES PATENTS 3,448,898 6/1969 Bernette..222/DIG. 12 3,399,808 9/1968 Buoys ....222/DIG. 12 2,743,492 5/1956Easton ..222/DIG. 15

[111 3,708,088 1 Jan.2, 1973 I FOREIGN PATENTS OR APPLICATIONS 718,74411/1954 Great Britain... ..164/309 Primary Examiner-Samuel F. ColemanAssistant ExaminerDavid A. Scherbel Attorney-David S. Kane, Daniel l-l.Kane, Philip T.

Dalsimer, Joseph C. Sullivan, John Kurucz, James J. Salerno, Jr., MartinB. Goldstein, Charles R. Hoffmann, Gerald Levy, Charles P. Bauer, PeterSaxon and Peter C. Van Der Sluys ABSTRACT 3 Claims, 3 Drawing Figures Ii30 CONTROL n cmcu/r 27- 29 24 44 1a an 26 v p [5b 15a 9 12 1 m4 c b 35/$1 34 a -/0 p a I W 32 A 3/ l I 1 I I I I I I I I I I I PATENTEDJAH2191s SHEET 1 OF 2 PATENTEDJAN 2191a SHEET 2 OF 2 FIG. 3.

----//5 VOLT L//VE---- ISV 4% APPARATUS FOR METERING LIQUID FLOWDISCHARGE BACKGROUND OF THE INVENTION The present invention relates toan improved system and method for dispensing liquid, such as moltenmetal,

in repetitively accurate equal amounts into a suitable mold. In the massproduction of castings made either in molds or in die casting machines,it is required to supply repeatedly accurate predetermined amounts ofpensate for the increase in height to which the metal level must beraised from its ambient level to the level of discharge.

DESCRIPTION OF THE PRIOR ART The system of the present invention issimilar to ex-.

isting systems for dispensing molten metal to molds in that inert gasunder pressure is introduced at the top of a closed vessel to displacethe liquid from the vessel through an outlet passage into a mold. Amajor problem encountered in the prior arts use of a sealed vesselimmersed in molten metal has been that the total cycle time must beaccurately increased pereach successive discharge of an equal volume ofmetal under constant pressure conditions. Increased time is neces saryto compensate for the additional height the molten metal must be raisedto reach the same discharge level because the liquid level of thereservoir drops lower upon each successive discharge.

Alternatively, it has also been proposed to maintain a constant timeduring which gas pressure is applied and increase the gaspressureapplied for each successive discharge; see, for instance, Doyen,US. Pat. No. 2,244,490, issued June 3, 194].

A typical constant pressure system included a metal melting furnacehaving means for automatically ladling a predetermined amount of metalfrom a chamber within the melting furan ce. Gas pressure is then used tocause molten metal discharge through a discharge channel located withinthechamber. Control of the gas pressure for the time necessary todischarge the predeterminedamount of molten metal was achieved bypositioning a float within the chamber such-that its position varied inaccordance with the level of the mo]- ten metal. Actuating meansinterconnecting thefloat and gas pressure pump varied the time of gaspressure application in accordance with the molten metal level asdetermined by the Heat. The actuating means made use ofa circuitincluding a timer responsive to the level of the moltenmetal in thechamber for automatically terminating the operation of the pump after aperiod of time determined by the setting of the timer and the level ofthe molten metal; see, for example, Tama, US. Pat. No. 2,937,789, issuedMay 24, 1960.-

Another constant pressure system monitored the rate of flow ofdischarging metal and compared this against reference signals in orderto make adj ustments through the use of complicated and expensiveelectrical circuitry; see, for example, Hibbard, U.S. Pat. No.3,465,916, issued Sept. 9, i969.

It is the primary object of this invention to provide a simple andinexpensive dispensing apparatus to repetitively dispense equal amountsof liquid metal.

It is a further object of this invention to provide a circuit controlemploying a simple timer mechanism which controls the presettime fluidpressure must be maintained to dispense a desired amount of liquid,which timer is activated by thestart of liquid discharge.

It is a further object of this invention to provide a simplifieddispensing apparatus which allows metal flow alternately in and out ofasingle opening.

It is'a further object of this invention to provide a dispensing systemand method of metering repetitive equal discharges of liquid metalsincluding molten liquid metals.

SUMMARY OF THE INVENTION I partially fills the vessel. This liquid inletfurther func-' tions as a valve seat which engages the bottom end of amovable discharge tube. After liquid enters said vessel, the dischargetube is moved intoa first position to seal the vessel liquid inlet.Pressurized gas is then introduced through the vessel opening whichcauses discharge of the liquid through an orifice end of the dischargetube. Since substantially equal pressure is applied during a dischargestate and since the internal dimensions of the hollow vessel and thedischarge tube are known, a predetermined substantiallyconstant flowrate is achieved. A liquid sensor adjacent the discharge orifice is usedto electrically signal when the liquid is first starting to dischargefrom the orifice. This pour start signal initiates operation of a timingcircuit which is preset to correspond with the known-time it takes todischarge a predetermined amount of liquid under constant dischargepressure conditions from a' given reference point, i.e. the dischargeorifice. Upon timing out of the timer, halt control signals aregenerated which cause the valve control to exhaust the pressurized gasand further to unseat the discharge tube from blocking the vessel inlet.Thus, liquid discharge is halted by removing the discharge pressure andby disconnecting the discharge path of flow. Simultaneously, liquid canrefill the vessel by flowing through the now open vessel inlet inpreparation for the nextcycle of discharge. Thus, a simple timeractivated by the first metal to flow from the discharge orifice controlsthe duration of the discharge condition in an accurate manner. 'Asimplified design employing a movable discharge tube allows a singlevessel valve inlet to act as both a liquid inlet and outlet.

BRIEF DESCRIPTION OF THE DRAWINGS Other features of the invention willbecome apparent from the following more detailed description and fromthe accompanying drawings, in which:

FIG. 1 is a view in vertical section of the apparatus of the inventiondisposed in a holding pot or furnace containing molten metal;

FIG. 2 is a partial view in vertical section of the discharge tube andof the FIG. 1 vessel inlet apparatus in an open inlet position; and

FIG. 3 is a detailed circuit schematic partially in block form of theFIG. 1 control system.

DESCRIPTION OF THE PREFERRED EMBODIMENT 'The purpose of the inventionshown in FIG. 1 is to repetitively discharge equal volumes of metal froma holding container into each mold 11 passing by on a conveyor means 12by use of metal dispensing apparatus partially submerged in the liquidmetal within the container.

The metal dispensing apparatus consists of a vessel 13 partiallysubmerged in molten metal 14 held by container l0. Vessel 13 consists oftwo hollow interconnected chambers 15 and 16. Fixed supports 9 locatedabove the container 10 mount the vessel 13. Chamber 15 functions as aholding chamber which extends slightly above the molten metal level. Atop opening 15a is provided in flanged top 15b mounted on holdingchamber 15 which communicates with a pressurized fluid line 18 withfluid entrance and evacuation controlled by solenoid valve 19.Interconnected generally horizontal chamber 16 of the vessel has atapered valve seat inlet 17 located adjacent an end remote from theinterconnection of chambers 15 and 16. The location of valve seat inlet17 allows metal 14 to enter through the top of chamber 16. By locatingthe valve inlet substantially below the metal level in the container 10slag, which frequently forms on the surface of the metal, does not enterthe dispensing apparatus.

Means defining a discharge channel in the form'of a vertically movabledischarge tube 20 is partially submerged in the metal 14. A two-way airpiston 21 under the control of a conventional solenoid valve 22 isconnected to the top of the tube 20 and moves the tube between anoperative seated condition (FIG. 1) and an inoperative condition (FIG.2). The discharge tube has a tapered inlet end 23 which engages thetapered valve seat inlet 17 to seal the vessel. A short downwardlyinclined discharge channel 24 interconnects the vertical passage 25within the tube at its top. The open end of channel 24 defines a pouringorifice 26 through which metal exists from the discharge tube to becaught by each conveyor mounted mold.

To'prevent metal solidification or build-up in the discharge portion ofthe tube above the metal level, the upper end of the discharge tube isenclosed in an insulating refractory-lined housing 27 in which are twogas burners (not shown) blowing through opposed side wall housing holes29. The gas burners maintain at least a minimum melting temperature inthe upper area of the dischargetube. An opening 30 through the top ofthe housing is provided to allow entrance of the piston rod of airpiston 21. Enough clearance is provided between the housing top andthetop of the discharge tube to allow the vertical reciprocation previouslyset forth. The refractory housing is three sided with an open fourthside to the right of FIG. 1 to allow the pro- 5 jection of dischargechannel 24 over the mold 11.

Other means, such as an electric resistance coil (not shown), could alsobe employed to heat the upper portion of the discharge tube.

Both discharge tube 20 and vessel 13 can be made of a graphitic or otherrefractory material resistant to attack by molten metal. Excellentresults were obtained in the preferred embodimentwith the use of a castmaterial comprising a silicon-nitride-bonded silicon carbide to form thevessel and discharge tube.

The above-described dispensing apparatus functions to automaticallydispense predetermined successive volumes of liquid metal. The cycle ofoperation starts after metal has been allowed to enter the vesselthrough the valve inlet 17 as shown in FIG. 2. A control circuit (to belater described) upon receiving a signal that a mold 11 is in a metalreceiving position generates two successive cycle control signals, thefirst of which signals energizes solenoid 2SV which causes solenoidvalve 22 to operate air piston 21 to move the discharge tube to theposition shown in FIG. 1 to seal valve inlet 17. The second of saidcycle control signals causes fluid control solenoid valve 19 to effectfluid pressurization of chamber 15. In the preferred form, the fluidused is pressurized gas stored in tank 31. Connected to tank 31 is ahigh pressure gas container 32. A high pressure reducing valve 33 in theline between tank 31 and container 32 maintains a constant pressure intank 31. A gas line 34 connects tank 31 with an inlet port b of valve19. The second cycle control signal causes a solenoid ISV to overcomethe resistance of spring 35 and move the valve spoolfrom the positionshown in FIG. 1

to the right, thereby blocking exhaust port 0 and allow ing gascommunication between ports a and b thereby pressurizing the vessel. Gasevacuation of vessel 13 occurswhen solenoid ISV is deenergized (as laterexplained), thereby allowing spring 35 to return the valve spool totheleft closing port b and exhausting gas from port a through port 0. v

Generally'an inert compressed gas is employed for molten zinc andaluminum such as nitrogen or dry air. For molten magnesium, a gas thatis substantially free of water vapor is preferred.

Introduction of gas under constant pressure to the vessel chamber 15forces the liquid metal inside. the vessel to flow at a uniform rate outof discharge orifice 26 where it is captured by mold 11. An electrodeelesolenoids ISV and 28V thereby venting gas pressure' through port c ofsolenoid valve 19 and raising discharge tube 20 to the inactive FIG. 2position. Metal then enters the vessel through valve inlet 17 to refillthe chambers in preparation for the next cycle of operation.

DETAILED CIRCUIT SCHEMATIC FIG. 3 illustrates a detailed schematic ofthe control circuit of FIG. 1 and represents the circuit in the inactivestate. Depression of push button 40 by the operator or by a mold passinginto a liquid catching position energizes the circuit from a 115 voltline power source. Depression of push button 40 closes normally openpush button contact set 40a, thereby energizing a first control relay41, first solenoid 18V and second solenoid ZSV which are connected inparallel. Energizing control relay 41 closes normally open first controlrelay contact set 410, thereby energizing a holding circuit to maintaincontrol relay 41 and the solenoids lSV and 28V energized when the pushbutton 40 returns to its open position. (It should also be noted thatdepression of push button 40 momentarily opens normally closed pushbutton contact set 40b which set again closes upon release of the pushbutton.)

It will be recalled that energization of solenoids 18V and ZSV cause thevessel to be pressurized and the discharge tube to be moved to close thevessel valve inlet.

Energization of first control relay 41 closes normally open firstcontrol relay contact set 41b, thereby allowing current to flow througha normally closed second control relay contact set 46 in order toenergize transformer 43.

Energization, of thefiprimary windings 43a of the transformer causes a10,000 volt potential in the secondary windings 43b. Electrodeelement 44is connected to one end of the secondary windings 43b with the other endgrounded.

Since the gas pressure solenoid lSV has been energized, liquid'metalbegins to flow from the discharge orifice. This metal flow is detectedby the energized electrode element 44 located adjacent the dischargemally closed second control relay contact set 46 to i open, therebydeenergizing the transformer 43 to stop electrode element arcing. Thisdrops out third control relay 47, thereby causing third control relaycontact set 47a to return to its normally open condition.

At this time, the circuit is under the control of the delay relay 42a.At the end of the preset time, the timer times out causing time delayrelay contacts 42 and 42b to open. Opening of time delay relay contactset 42b deenergizes second control relay 4612 thereby opening secondcontrol relay contact set 46b.and closing second control relay contactset 46. i 7

Opening of timer delay relay contactset 42 causes deenergization offirst control relay 41, thereby opening the first control relay contactset 41a and first control relay contact set 41b. Thus it can be seenthat opening of the contact sets 42 and 42b functions as a second signalin the form of a halt control signal which deenergizes the gas valvesolenoid 18V and the air valve solenoid 2SV which causes stoppage ofmetal dispensing. Deenergization of the second control relay 2 SV. Thecontrol circuit is again in the inactive state shown in FIGJ3 inreadiness for the next cycle of metal dispensing.

former 43. Arcing of the. electrode element acts as a firstcontrolsignal representative of the start of metal dispensing time. Theshort circuit current provides a 6 volt drop across a 5 ohm resistor 45in series with the- This timer delay relay has been preset for thepredetermined time it takes to dispense the desired volume of moltenmetal needed to fill the conveyor mold. Energization of second controlrelay 46a causes While switch 40 is described above for simplicity asmanually actuated, in practice it will be normally actuated to itsclosed position automatically as each mold 11 is moved into metalreceiving position. f

In summary, an apparatus for liquid dispensing from a sealed vessel isprovidedwhich has a cycle of operation requiring the sealing of the onlyliquid inlet to the vessel with a movable discharge channel definingmeans; displacing the liquid in the vessel by use of pressurized fluidbeing introduced to the vessel to force the liquid through an orifice ofthe discharge channel; generating a first signal by means of theelectrode element 44 andthe circuit already described which signal is afunction of the start of the liquid pouring through the dischargeorifice; maintaining liquid discharge for a preset time measured by atimer being energized so that a second signal which is a time delaysignal representative of the preset time needed to discharge the desiredamount of.liquid is generated; and relieving the gas pressure on theliquid when the second signal is normally open second controlrelaycontact set 46b to I become closed, thereby maintaining a holdingcircuit for the timer delay relay 42a and the second control relay,46a.This holding circuit is necessary because energization of second controlrelay 46a causes norgenerated by causing solenoid means to evacuatepressurized gas from the vessel and to move the discharge channel fromengagement with the vessel inlet, such movement of the discharge channelallowing the vessel to again be refilled with liquid metal. 7

It is to be understood that the above detailed description of thepresent invention is intended to disclose an embodiment thereof to thoseskilled in the art, but that the invention is not to be construedaslimited in its ap-" plication to the details of construction andarrangement of parts illustrated in the accompanying drawings,

since the invention iscapable of being practiced and carried out invarious ways without departing from the spirit of the invention. Thelanguage used in the specification relating to the operation andfunction of the elements of the invention is employed for purposes ofdescription and not of limitation, and it is not intended to limit thescopeof the following claims beyond the requirements of the prior art.

What is claimed is: Y

1. Apparatus for repetitively dispensing a predetermined amount ofliquidmetal for use with a metal melting furnace comprising a vessel defininga chamber to hold liquid metal, said vessel being partly submerged in acontainer of the liquid to be discharged, said chamber having a liquidinlet below the level of the liquid in said container through whichliquid enters to at least partially fill said chamber, means defining adischarge channel disposed adjacent and in fluid communication with saidchamber, said discharge channel having a pouring orifice at one endremote from said chamber, and said discharge channel defining meanspartly immersed in said liquid, means applying a uniform fluid pressureto a surface of said liquid metal in said chamber to cause the liquidmetal to be discharged from said chamber through said discharge channel,a pour flow detector means positioned adjacent said pouring orifice fordetecting the presence of liquid metal discharging from said orifice,actuating means operatively connected to said pour flow detector meansand responsive to the start of liquid metal discharge from said orificeas sensed by said pour flow detector means for causing said fluidpressure applying means to maintain metal discharge only for a presettime interval through said orifice, thereby discharging a predeterminedamount of liquid metalfrom said chamber regardless of the initial levelof the liquid metal in said chamber, said discharge channel having aninlet end 8 which, in one position, engages and precludes liquid flowbetween said container and said vessel through said chamber inlet whileestablishing liquid communication between said chamber and saiddischarge channel and, in a second position, is remote from and openssaid chamber inlet to liquid flow from said container, and means formoving said discharge channel defining means between said first andsecond positions.

2. The apparatus as recited in claim 1 wherein said actuating meansfurther comprises cycle control means for generating two successivecycle control signals, the first of said cycle control signals causingsaid means for moving said discharge channel to place said dischargechannel in said first position, and the second of said cycle controlsignals causing said fluid pressure applying means to pressurize saidchamber, thereby forcing liquid through said discharge channel.

3. A liquid metal dispensing apparatus for use with a holding potcontaining liquid metal comprising:

a. an enclosed vessel that is partially submerged in the liquid metal,said vessel having means defining a gas opening above the liquid metallevel, said vessel having a valve seat inlet located below saidliquidlevel through which liquid metal enters to at least partially fillsaid vessel;

b. means defining a movable discharge tube partially immersed in saidliquid metal, said discharge tube having an inlet end which communicateswith and seals said vessel inlet to metal influx in one position and isremote therefrom in a second position, said discharge tube having adischarge orifice remote from said inlet end and c. means for movingsaid discharge tube between said first and second positions.

1. Apparatus for repetitively dispensing a predetermined amount ofliquid metal for use with a metal melting furnace comprising a vesseldefining a chamber to hold liquid metal, said vessel being partlysubmerged in a container of the liquid to be discharged, said chamberhaving a liquid inlet below the level of the liquid in said containerthrough which liquid enters to at least partially fill said chamber,means defining a discharge channel disposed adjacent and in fluidcommunication with said chamber, said discharge channel having a pouringorifice at one end remote from said chamber, and said discharge channeldefining means partly immersed in said liquid, means applying a uniformfluid pressure to a surface of said liquid metal in said chamber tocause the liquid metal to be discharged from said chamber through saiddischarge channel, a pour flow detector means positioned adjacent saidpouring orifice for detecting the presence of liquid metal dischargingfrom said orifice, actuating means operatively connected to said pourflow detector means and responsive to the start of liquid metaldischarge from said orifice as sensed by said pour flow detector meansfor causing said fluid pressure applying means to maintain metaldischarge only for a preset time interval through said orifice, therebydischarging a predetermined amount of liquid metal from said chamberregardless of the initial level of the liquid metal in said chamber,said discharge channel having an inlet end which, in one position,engages and precludes liquid flow between said container and said vesselthrough said chamber inlet while establishing liquid communicationbetween said chamber and said discharge channel and, in a secondposition, is remote from and opens said chamber inlet to liquid flowfrom said container, and means for moving said discharge channeldefining means between said first and second positions.
 2. The apparatusas recited in claim 1 wherein said actuating means further comprisescycle control means for generating two successive cycle control signals,the first of said cycle control signals causing said means for movingsaid discharge channel to place said discharge channel in said firstposition, and the second of said cycle control signals causing saidfluid pressure applying means to pressurize said chamber, therebyforcing liquid through said discharge channel.
 3. A liquid metaldispensing apparatus for use with a holding pot containing liquid metalcomprising: a. an enclosed vessel that is partially submerged in theliquid metal, said vessel having means defining a gas opening above theliquid metal level, said vessel having a valve seat inlet located belowsaid liquid level through which liquid metal enters to at leastpartially fill said vessel; b. means defining a movable discharge tubepartially immersed in said liquid metal, said discharge tube having aninlet end which communicates with and seals said vessel inlet to metalinflux in one position and is remote therefrom in a second position,said discharge tube having a discharge orifice remote from said inletend; and c. means for moving said discharge tube between said first andsecond positions.